Signaling system



April 1935- I s. VAN MIERLO E. TAL 1,997,205

S IGNALING SYSTEM Filed NOV. 29, 1933 IIHI' IIHI' S. VAN M/ERLO INVENTORS J. M R. G/RARD C. A. J. PULLES By 6%.M

ATTORNEY Patented Apr. 9, 1935 CSIGNALING SYSTEM Stanislas Van Mierlo; Jean M. R. Girard, and

Cornelis A. J. Pulles, Paris, France, assignors to Western-Electric Company, Incorporated, New York, N. Y., a corporation of New York Application November 29, 1933, Serial No. 700,246

France December 15, 1932 '7 Claims. (CLUB-16) This invention relates to signaling systems and more particularly to circuit arrangements for transmitting and receiving direct current impulses over lines, the sections of which are in- 5 ductively connected by-repeating coils or transformers.

In telephone systems in which connections are established between widely separated points over interconnecting trunk circuits. it is necessary in order to obtain efficient transmission to employ in the trunk circuits repeaters'involving repeating coils. If the connections over the trunk circuits are to be established by means ofinachine switching apparatus it then becomes necessary to repeat dialing impulses around or through the repeater connections between the sections of the established circuit.

It is well known that if an impulse of direct current is transmitted through the primary winding of a repeating coil that one impulse will result in the secondary winding of the coil on the closure of the direct current path through the primary winding and that a second impulse will result in the secondarywinding on the opening of a direct current path through the primary winding. This would obviously result in the reception in the circuit associated with the secondary winding of twice the number of impulses transmitted. I

In accordance with the present invention in which'direct current impulses are dialed into a path through the primary-,windingof a repeating coil, the receiving equipmentassociated with the secondary winding is arranged to respond only to the impulses resulting in the secondary winding due to the breaks or openings of the circuit through the primary winding. This is accomplished by the provision of a rectifier connected in series with the impulse responsive relay which is bridged across the secondary winding of the repeating coil, the rectifierbeing so poled that current can flow therethrough and through the windingof the responsive relay only when the circuit through the primary winding of the coil is opened by the opening of the impulse'transmitting device contacts, for example, the impulse dial contacts. Y I

In accordance with a further feature of the invention, provision is made for correcting-the impulses received by the responsive relay so that should they be too short to properly operate receiving equipment such as a selector switch or impulse repeater, they maybe corrected to a predetermined duration which is independent of the duration of the impulses received. This is accomplished by providing a secondary impulse responsive relay which is polarized or biased by a rectifying device connected in parallel with the windings thereof and which is responsive to the operation of the primary impulse responsive relay. 5 The secondary relay in turn may operate a quickacting impulse repeating relay if it is desired to repeat the received impulses over a further sec tion of the trunk or may directly operate the stepping magnet of a selector switch. A

In accordance with a further feature of the invention long signaling impulses of closely spaced directcurrent impulses orIof alternating current of a suitablefrequency to which the direct current impulse responsive device will continu- 15 ly pond may be transmitted; These impulses may be employed as desired to. operate suitablesignaling apparatus at the distant or at intermediate points in the trunk circuit.

The invention will be more clearly understood from the following description of one embodiment thereof shown in the accompanying draw mg. a

At the extreme left of the drawing is shown an impulse transmitting station. In the central portion of the drawing a repeating station is shown and at the extreme right of the drawing'a receiving station is shown. The trunk conductors between the transmitting station and the repeat ing station are connected by repeating coils I00 and I0! and the trunk conductors between the repeating station and receiving station are connected by repeating coils lilZ- and H33. It will, .of course, be obvious thatadditional repeating. stations, similar to that disclosed, could be inserted with the required repeating coils between the repeating station disclosed and the receiving station. 7 1

When the dial I05 at the transmitting station is moved from normal to transmit impulses to set a selector switch at the distant receiving station, ground is connected over the off-normal contacts of the dial to the back contact of relay m6, but relay I06 beingfoperated this ground is ineffective at this time. When, however, the dial returns to normal the circuit of relay (06 is interrupted intermittently bythe impulse contacts of the dial and upon each interruption the oil"- cuit from the off-normal ground of the dial is extended over the back contact of relay I06, 50

through the winding of relay I01 and the left winding of relay I08 to battery. Relay ")8 responds to the impulse and renders itself slow to release by short phasing its right winding so that it remains operated-throughout the train of im- Cir pulses and connects condenser H39 and resistance H9 in shunt of the primary winding of repeating coil i9?! toprevent high currents and high tensions in the trunk.

Relay It)? operates and releases at the beginning and end of each impulse, connecting and disconnecting battery and ground to andfrom the primary winding of repeating c'oil' IGB through the normal contacts of key. IH so that short, direct current impulses are transmitted through the secondary winding of repeating soil It!!! and the primary winding of repeating coil IElI' at each make and breakof the current in j the primary winding of repeating coil I65. It is to be understood that the primary windingof repeating coil I should be practically saturated at each impulse. The two impulses transmitted for each dialed impulse are opposite in- At the repeating station each impulse is in duced into the secondary winding of repeating coil Eel andpasses through the winding of primary impulse responsive relay H2 in series with the rectifier H3 which is poled so as to pass the impulses resulting fr'ointhe breaks of the dial contacts and to reduce the strength of orbar the impulses resulting from the makes of the dial contacts. v Relay f I2 upon each operation closes its contacts just suffi'ciently to operate the secondary; impulse responsive relay II i, relay I M having a small number of turns to render it quick to operate. Tolimit the current'flowing through the winding of relay H4 to a desired value, resistances H5 may be placed'in series therewith. Relay I M is given a'releasing' time equal to the length of impulse desired by the rectifier I I6 which is connected in parallel its winding. Each" short impulse" received over the trunk by the relay I I2 therefore producesan impulse corrected to-a predeterinine'd'length in the receiving equipment controlled by the com tacts of reIayfII I. I

The difference between successive impulses re; ceived by relay H2 is verysniall and the difference in the operation of relays I I 2 and I I4 is also very small during a train ofimpul'ses. V The time between successive impulses is therefore very little distorted even with many repetitions of impulses.

At its contacts relay I I4 closes a series circuit through the windings of relays II! and i I9. Re lay H8 upon operating renders itself slow to re-'- lease by short circuiting its left winding and con nectsan impulse shaping shun-t comprising condenser IIS' and resistance mil-aroundthe pri'-. mary winding of repeating coil I62. Slow to-r'e lease relay I2I- being normally operated, battery and ground are connected over its alternate contacts and the front contacts of relay Hi to the primary winding of repeating coil I 62 during each operation of relay I I4, and consequently, make and" break direct current impulses are transmitted through the secondary winding of repeating coil :02 and the windings of repeating coil 103' to theequipment at the receiving stanon;

At the receiving station each impulse passes,

through the winding of primary impulse respon sive relay I22 in serieswith the recti-fler 33 which is so poled as to pass the break impulses and to reduce the strength. of or bar the make impulses. Relay I 22- upon' each operation-closes its contacts just sufiiciently to operate the secondary impulse responsive relay I24, relay I24 having a small number of turns to render it quick to operate. To limit the current flowing through the winding 'of relay I24 to a desired value, resistances may be placed in series therewith. Relay I24 is given a releasing time equal to the length of impulse desired by the rectifier I25 which is con- .nected in parallel with its winding. Each short impulse received by relay I22 therefore produces an impulse corrected to a predetermined length in the receiving equipment controlled by the contacts of relay I24. At the front contact of relay I 24 upon each energization thereof, a circuit is established for stepping magnet, I21 of a selector switch or other apparatus which it is desired to ope atein response to dialed impulses.

"To transmit a signal from the transmitting station to the receiving station for any purpose as, for example, to attract the attention of an operator or attendant, the key III is operated. The operation of this key closes the circuit of relays Inland K38 which operate, relay I68 establishing the impulse shaping circuit including condenser I09 and resistance II!) in shunt of the primary winding of repeating coil I00 as previously described, but relay I67 performs no useful'func'tion at this time since with key III operated it cannot connect battery and ground to the primary winding of repeating coil I00. At its inner alternate contacts key III connects the source I'28- of alternating current to the primary winding of coil IMI; This source of current may be of 32-cyc1e frequency which may be obtained from a lG-cycle-rin'ging machine by a common transfon'ner'and two rectifiers or alternatively a Si l-cycle supply of alternating current, if available, may be used. I V 7 Current from the source- I28 operates relay H2 steadily which, in turn, holds relays II4, I I1 and H8 operated. With relay I I! operated, slow-torelease relaylfif releases, disconnecting battery and ground from the primary winding of repeating coil I62 and connecting the source I29 of alternating current thereto. This source may be similar to the source I28} In response to the connection of sourceof current I'29' relay I22 is steadily operated and, in" turn, maintains relay I24 operated. Relay I24 being steadily operated opens the circuit of slow-to-rel'ea's'e relay I30 for a time sufii'cient to permit the release of this'rel'ay which at its back contact closes the circuit of a suitable signaling device such as the lamp I3I. 7

Since battery is connected to the primary windingof repeating coils I00 and I02 for a minimum time long enoughto reach at its disconnection a current value which is near the maximum, the strength of the impulse is not influenced much by variations in the potential of the battery and by the length of the time the contacts of relays IE1! and H! are closed. Also since relays H4 and I24 are'nearly saturated their operating and releasing times do not depend much on the battery voltage. The. system does not require any special source of current, such as I28 or I29 as when long signals are to be transmitted the regular battery may be connectedin place of the sources I'i and I29 through the operation of key I! I andrelease of relay IN and closely spaced impulses transmitted therefrom. a

From the foregoing it will appear that the system is very simple, does not require any special source-of current or special relays having delicate adjustment and requiring abnormal maintenance and that dialing may be effective at dialing speeds between 8 and liimpulses or more per second.

Instead of using serially connected rectifiers in the circuits of relays I I2 and I22 these relaysmay be biased by a 4-volt accumulator or these relays inverse or make impulses and to increase the eiTect of the desired or break impulses. Relays I I4 and I24 may also be made slow-to-release by other means than the parallelly connected rectifiers H6 and 126 as by providing them with auxiliary short-circuiting windings such as shown on relays I88 and H8,

What is claimed is? 1. In a signaling system, a transmitting station, a receiving station, a line extending between said stations and divided into sections, a repeating coil for uniting said sections, means at said transmitting station for transmitting impulses or direct current to the primary winding of said repeating coil, and an impulse responsive relay connected in series with a rectifier in circuit with the secondary winding of said repeating coil at said receiving station, said relay being so polarized by said rectifier as to be responsive only to the break impulses set up by said transmitting means.

2. In a signaling system, a transmitting station, a receiving station, a line extending between said stations and divided into sections, a repeating coil for uniting said sections, means at said transmitting station for transmitting impulses of direct current to the primary winding of said repeating coil, a primary impulse responsive relay connected in circuit with the secondary winding of said repeating coil at said receiving sta tion and so polarized as to be responsive only to the break impulses set up by said transmitting means, a secondary impulse responsive relay controlled by said primary impulse responsive relay, and a rectifying means connected in parallel with the winding of said latter relay and so poled as to render said relay slow to release.

3. In an impulse correcting system, means for transmitting short impulses of current, a primary relay responsive to said impulses, a quick operating secondary relay operable in response. to each operation of said primary relay, impulse transmitting contacts controlled by said secondary relay and a rectifier connected in parallel with the winding of said secondary relay so poled as to retard the release of said secondary relay following each release of said primary relay whereby impulses of predetermined duration are retransmitted by said secondary relay.

4. In a signaling system, a transmitting station, a repeating station and a receiving station,

a line extending between said transmitting station and said repeating station and having a first repeating coil therein, a line extending between said repeating station and said receiving station and having a second repeating coil therein, means at said transmitting station for transmitting impulses of direct current to the primary winding of said first ,repeating coil, an impulse responsive relay at'fsaid repeatingstation connected-to the secondary winding of said'first repeating coil and so polarized as to be responsive only to the break impulses set up in said first repeating coil by said transmitting means, means controlled by said impulse responsive Zrelay to transmit impulses of 'direct 'current to the primary winding of said second repeating coil and an impulse responsive'relay at saidreceiving station connected .tofthesecondary winding of said second repeating coil and so polarized as to be responsive only to the break impulses set up in the second repeating coil.

5. In a signaling system, a transmitting station, a repeating station, and a receiving station, a line extending between said transmitting station and said repeating station and having a first repeating coil therein, a line extending between said repeating station and said receivtherein, means at said transmitting station for transmitting impulses of direct current to the primary winding of said first repeating coil, a primary impulse, responsive relay connected in series with a rectifier in circuit with the secondary winding of said first repeating coil at said repeating station, said latter relay being so polarized by said rectifier'as to be responsive only to the break impulses set up in said first repeating coil by said transmitting means, a secondary im pulse responsive relay controlled by said primary relay to transmit impulses of direct current to the primary winding of said second repeating coil, and an impulse responsive relayconnected in series with a rectifier in circuit with the secondary winding of said second repeating coil at said receiving station, said latter relay being so polarized by said rectifier asto be responsive only to the break impulses set up in said second repeating coil by said secondary impulse relay.

6. In a signaling means, a transmitting station, a repeating station, and a receiving station,

a line extending between said transmitting stasaid transmitting station for transmitting an impulse of pulsatory current through the primary winding of said first repeating coil, a first impulse responsive relay at said repeating station connected to the secondary winding of said first repeating coil and so polarized as to be steadily responsive to'said current, a slow-to-release relay arranged to release upon thecontinuedoperation of said impulse responsive relay and while released to transmit an impulse of pulsatory current to the primary winding of said second repeating coil, a second impulse responsive relay at said receiving station connected to the secondary winding of said second repeating coil and so polarized as to be steadily responsive to said current, a slow-to-release relay arranged to release upon the continued operation of said second impulse relay, and a signal controlled by the release of said last relay. I

7. In a signalingmeans, a transmitting station, a repeating station, and a receiving station, a line-extending between said transmitting sta tion and said repeating station and having a repeating coil therein, a line extending between said repeating station and said receiving station, and having a repeating coil therein, means at said of alternating current through theprimary winding of said first repeating coil a first impulse responsive relay at said repeating station connected to the secondary winding of said first re- .peating coil and so polarized; as to be steadily, responsive to said current, a slow-to-release relay arranged to release upon the continued operation of said impulse responsive relay and while released to transmit an impulse of alternating current to the primary winding of said repeating coil, a secondimpulse responsivetrelay at said receiving j station connected to the secondary winding of said second repeating coil and so polarizedas to be steadily responsive to said current, a slowr-to-release relay arranged to release upon the continued operation of said second impulse relay and a signal controlled by the release of said last relay.

STANISLAS VAN MIERLO. JEAN M. R. GIRARD. CORNELIS A. J. PULLES. 

